Specific secretion of citric acid induced by Al stress in Cassia tora L.
Specific secretion of citric acid induced by Al stress in Cassia tora L.
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DOI：
10.1093/oxfordjournals.pcp.a029266
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发表时间：
1997-09-01
影响因子：
4.9
通讯作者：
Matsumoto, H
中科院分区：
文献类型：
--
作者：
Ma, JF;Zheng, SJ;Matsumoto, H
建立了一种快速、灵敏的铝螯合活性测定方法，以筛选铝胁迫下抗铝植物根系分泌的铝螯合物质。从一种抗铝植物决明子（Cassia tora L.）当将根分泌物暴露于pH 4.5的0.5mM CaCl 2溶液中的50 μ M Al时，在根分泌物中检测到Al螯合物质;鉴定出主要组分为柠檬酸。柠檬酸的分泌是非常低的，在第一个4小时开始后，铝处理，但此后显着增加。一个3小时的脉冲与50 μ M铝也诱导显着的柠檬酸分泌后6小时。铝添加和柠檬酸分泌之间的滞后表明，诱导过程参与。剂量-反应实验表明，柠檬酸的分泌量随外源铝浓度的增加而增加。缺磷处理8 d不诱导柠檬酸的分泌。暴露于50 μ M的镧（La 3+）或镱（Yb 3+）也没有诱导柠檬酸的分泌。这些结果表明，柠檬酸的分泌是铝胁迫的特异反应。tora，并构成了耐铝机制。
A rapid and sensitive assay method for Al-chelating activity was established to screen Al-chelating substances secreted from roots of Al-resistant species in response to Al stress. From one Al-resistant species, Cassia tora L., an Al-chelating substance was detected in the root exudates when they were exposed to 50 mu M Al in 0.5 mM CaCl2 solution at pH 4.5; the dominant component was identified as citric acid. The secretion of citric acid was very low during the first 4 h after initiation of Al treatment, but increased markedly thereafter. A 3-h pulse with 50 mu M Al also induced significant secretion of citric acid after 6 h. The lag between Al addition and secretion of citric acid suggests that inducible processes are involved. A dose-response experiment showed that the amount of secreted citric acid increased with increasing external concentrations of Al. Eight-d treatment of P deficiency did not induce the secretion of citric acid. Exposure to 50 mu M of either lanthanum (La3+) or ytterbium (Yb3+) did not induce the secretion of citric acid either. These findings indicate that the secretion of citric acid is a response specific to Al stress in C. tora and constitutes a mechanism of Al resistance.